SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a443eb67a114915d63b886148d0f9d4e646b409767ae975f75867bc8b20bebc0' 
  AND token = 'g7YKM+rCy2ejWb8GTZqGSQuE85v5ge3UYFqK9qrDgEs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}